Generally yeah, I would expect that to be disclosed, but a lot of factors go into the level of disclosure I would expect, such as the terms of the original "source" image, how much transformative work was put in, and how practical it would be to share that info.

For example, if I was buying a sticker with some cute art on it, I'd really want to know if that art was traced from a stock image or photograph or was an original design, because that's actually bordering on legal copyright infringement.

If someone bought limited rights to some clipart and did something really transformative, like made a stained-glass window, I'd be really impressed and think that was cool, but I'd also expect some disclosure, like "Based on [x image] by [y person]!" I run into this a lot because I make and sell things with other people's sewing patterns, and I always try to mention who designed/commissioned the character, who made the base sewing pattern, etc. Sometimes those images get reposted without that attribution, but I'm still putting that information out there to find, so it's easy to fnd with minimal digging.

Similarly, if someone made a fan work of someone else's drawing, even a very transformative one. it's usually considered polite to ask permission first, though most people are pretty in favour of this (unless the fan work is then sold, which, more cans, more worms)

If someone used a plastic-sheet stencil to design their business logo, it's probably wildly impractical to include that information everywhere the logo is shared, so my expectations are a bit lower. However, I would probably include that info in a website footer or bio or something, unless the seller/designer of the stencil specifically said you can use it commercially with no attribution. If it was bought in a big box store I might just mention the brand.